1. Field of the Invention
The present invention relates generally to spring motors and particularly to spring motors which are adaptable for use in toys such as toy vehicles.
2. Description of the Related Art
U.S. Pat. No. 4,135,329 issued to Kennedy on Jan. 23, 1979 ("the '329 patent") describes a spring motor that is relatively easily and inexpensively manufactured, and that efficiently delivers a high portion of the energy stored in its spring to the ultimate drive and which is easily and efficiently rewound by a child. The '329 patent eliminated the disadvantageous characteristics of the then prior art motors and comprised a device that has characteristics that various prior art constructions sought to achieve. Essentially the '329 patent disclosed a spring motor for use as an example in a miniature toy vehicle that can be conveniently and reasonably wound up by a reciprocating front and back movement of the vehicle, wherein the backward movement produced substantially more winding up than an unwinding of the spring. The '329 patent disclosed a spring motor that avoided complicated and sophisticated structures in order to produce rewinding of the spring on a backward movement of the car.
U.S. Pat. No. 4,683,986 issued to Darda et al. on Aug. 4, 1987 ("the '986 patent") discloses a spring drive mechanism having a spiral spring positioned in a spring encasement as a power source. One end of the spring is connected to a spring encasement gear and the other end to a spring shaft gear. For winding up the spring, the spring encasement gear is in mesh with a first drive pinion and the spring shaft gear is in mesh with a second drive pinion. These drive pinions have a stress-free connection to a wind down/wind up shaft across unidirectional torque transmitters. Each of these unidirectional torque transmitters permits rotation in a direction opposite to the other. A reverse pinion has one pinion sprocket in mesh with the spring shaft gear. The other pinion sprocket is in mesh with the drive pinion in the wind up position. In this position, the spring drive mechanism is blocked in such a way that the tensioned driving spring cannot release. In order to maintain the reverse pinion in this position without any use of external force, an engaging lever is provided and is constructed in such a way that the blocking is released when the wind down/wind up shaft is turned counterclockwise.
The blocking feature of the '986 patent is a desirable feature, but the structure disclosed in said patent to accomplish the feature is relatively complicated and expensive to manufacture. There is a need for an improved spring motor that includes, inter alia, such a blocking feature without the complicated structures of the prior art. There is also a need to accomplish a faster rewind of the spring motor, again, without the complicated structures of the prior art.